Description: Shell translucent with a pale yellow-green tint;
full-grown shell 13 to 20 mm; umbilicus wide, 20 to 35% of shell diameter;
shell with
5.5 to 6 whorls;
young shells have spiral lines on the parietal (inner) wall of the aperture;
width of last whorl much more than twice the width of the penultimate whorl;
body whitish.

Natural History: Appears to be primarily fossorial in mixed
forests where it is associated with bigleaf maple (Acer macrophylum) trees,
under which
it
is
found on soil under leaf litter or in rodent burrows.

Conservation Status: The Oregon Natural Heritage Program
lists M. hemphilli as "Rare, threatened, or uncommon" throughout its
range as well as in Oregon.

Literature Cited:

Bureau of Land Management. 1999. Field Guide to Survey and manage Terrestrial
Mollusk Species from the Northwest Forest Plan. BLM. Eugene, Oregon.

According to Appendix J2, Megomphix hemphilli (Oregon megomphix) is restricted
to the Olympic National Park, and Olympic and Mount Baker-Snoqualmie National
Forests.

The draft Terrestrial Mollusk Survey Protocol (Version 2.0, 10/29/97, p. 43)
describes the range of this snail as the Puget Trough of western Washington
through the Willamette Valley, Cascade Range foothills, and Coast Range of
Oregon. Habitat is within moist conifer/hardwood forests up to 3000 feet in
elevation in hardwood leaf litter and decaying non-coniferous plant matter
under big-leaf maple trees near rotten logs or stumps. A big-leaf maple component
in the tree canopy and an abundance of sword fern on forested slopes and terraces
seem characteristic of Megomphix sites.